The invention relates to an arrangement for the recording of an information signal, in particular onto a plate-shaped, metallic recording carrier.
The cutting of an analog information signal into the surface of a plate-shaped recording carrier with the aid of a cutting stylus is known. The original cutting into a lacquer film has been replaced increasingly in recent years by cutting into a metallic recording carrier. This has increased the fidelity of shape of the cut-in groove and also eliminated several intermediate stages in the production of a phonographic record.
At the same time, digital sound and data recording, in which an information item is recorded onto a recording carrier by complicated optical and chemical processes with the aid of a laser beam and read out by a laser beam, is gaining increasingly in significance. Although this type of recording is distinguished by particularly good acoustic characteristics and improved handling of the finished recording carrier, the production of such a so-called CD (compact disc) is far more complicated than analog recording with the aid of a cutting stylus.
German Patent Specification 3,527,606 discloses a process for the recording of a digital information signal, in particular an audio signal in CD format, in which the signal is located, with the aid of an engraving stylus driven perpendicular to the recording carrier, between two successive indentations of the signal to be recorded above, and in the indentations beneath the undeformed surface of the recording carrier.
With the aid of this known process, the recording of a purely digital signal, the informational content of which is determined by the length and the spacing of two successive indentations on the recording carrier, is basically possible.
It is known that optical scanning systems evaluate diffraction patterns of the surface structure. It has been shown that the laser scanner standardized for the compact disc also detects signals from surface structures produced non-rectangularly in cross-section.